Carburettors provided with a starting device with an eccentric flap valve

ABSTRACT

The eccentric flap valve is situated in an air intake of the carburettor upstream of the intake system for the primary air/fuel mixture, and actuated by the air flow against the effect of a first thermostatic member which tends to close it when the temperature of an element of the engine is below a given limit. A &#39;&#39;&#39;&#39;fast idling&#39;&#39;&#39;&#39; cam cooperates with a second thermostatic member, to partly open the usual throttle member of the carburettor when the flap valve is at least partially closed. Pneumatic means sensitive to the pressure which exists in the intake pipe downstream of the throttle member control the opening of the valve when the pressure diminishes. Stop means with several positions, limit, in variable manner as a function of the position that they occupy, the movement of the pneumatic means. Means sensitive to the ambient temperature control the position occupied by the stop means.

United States Patent [191 Mennesson Nov. 19, 1974 [75] Inventor: AndreLouis Mennesson, Neuilly S/Seine, France [73] Assignee: SocieteIndustrielle De Brevets Et DEtudes S.I.B.E., Nanterre, France [22]Filed: June 26, 1973 [21] Appl. No.: 373,748

[30] Foreign Application Priority Data July 31, 1972 France 72.27507[52] US. Cl 261/39 B, 261/39 E 51 Im. Cl. F02m 1/10 [58] Field of Search261/39 A, 39 B, 39 E, 52

[56] References Cited UNITED STATES PATENTS 3,272,486 9/1966 Lucas et al261/39 B FOREIGN PATENTS OR APPLICATIONS 799.345 8/1958 Great Britain26l/39 E Primary Examiner-Francis S. Husar Attorney, Agent, orFirm-Stevens, Davis, Miller & Mosher 5 7] ABSTRACT The eccentric flapvalve is situated in an air intake of the carburettor upstream of theintake system for the primary air/fuel mixture, and actuated by the airflow against the effect of a first thermostatic member which tends toclose it when the temperature of an element of the engine is below agiven limit. A fast idling cam cooperates with a second thermostaticmember, to partly open the usual throttle member of the carburettor whenthe flap valve is at least partially closed. Pneumatic means sensitiveto the pressure which exists in the intake pipe downstream of thethrottle member control the opening of the valve when the pressurediminishes. Stop means with several positions, limit, in variable manneras a function of the position that they occupy, the movement of thepneumatic means. Means sensitive to the ambient temperature control theposition occupied by the stop means.

9 Claims, 3 Drawing Figures PATENIE rmv I 91974 sum 30; a

CARBURETTORS PROVIDED WITH A STARTING DEVICE WITH AN ECCENTRIC FLAPVALVE The invention relates to carburettors of the type which comprisean eccentric flap valve starting device located in the air intake of thecarburettor upstream of the system for the introduction of the primaryair/fuel mixture, which valve is actuated by the air flow inspired bythe carburettor against the effect of a first thermostatic member whichtends to shut this valve when the temperature of an element of theengine is less than a given limit, said carburettor comprising inaddition a cam called an accelerated or fast idling cam adapted tocooperate with a second thermostatic member, said cam being designed topartly open the usual throttle member of the carburettor when thestarting valve is at least partiallyclosed, pneumatic means sensitive tothe pressure which exists in the intake pipe downstream of the throttlemember being provided to control, by their movement, the opening of theflap valve when the abovesaid pressure diminishes.

Carburettors of this type have been described in our United StatesPatent Specification No. 3,185,453.

It is known that, soon after starting an engine which is still cold, itis necessary to partly open the fiap valve so that the richness of theair-fuel mixture supplied to the engine is not too high. The role of thepreviously considered pneumatic means is, precisely, to partly open theflap valve.

The regulations relating to atmospheric pollution require the supply tothe engine of mixtures whose richness is as low as possible, at leastfor temperatures in the neighbourhood of 20C. However, for lowertemperatures, it is necessary to supply to the engine, after starting,richer mixtures in order to avoid stalling.

In other words, the opening of the flap valve after starting, whichconditions the richness of the air-fuel mixture, must depend on theambient temperature at which the engine is started.

Devices are known which enable modification, as a function of theambient temperature, of the pressure which actuates the pneumatic meansconnected to the flap valve, but these devices are of little accuracysince the position of the flap valve depends to a large extent onfriction of the linking elements which actuate the flap valve.

It is a particular object of the invention to render carburettors of thetype concerned such that they respond to the various exigencies ofpractice better than hitherto and especially such that they give aprecise position of the flap valve after starting, which position mustdepend on the ambient temperature of starting and must be independent ofthe friction of the actuating elements of the flap valve.

According to the invention, a carburettor of the type defined above ischaracterised by the fact that it comprises stop means with severalpositions, adapted to limit in variable manner as a function of theposition that they occupy, the movement of the pneumatic means, andmeans sensitive to ambient temperature adapted to control the positionoccupied by the stop means.

Preferably, these stop means with several positions are constituted by astepped rotary cam, the various angular positions taken by the cam beingcontrolled by means sensitive to the ambient temperature.

Advantageously, the stepped cam is constituted by a peripheral portionof the cam of fast idling, different from the zone serving for theregulation of the opening of the usual throttle member; the meanssensitive to ambient temperature are then constituted by the secondthermostatic member of which one end is anchored at a fixed point and ofwhich the other end is unchored on the fast idling" cam.

The pneumatic means can be constituted by a diaphragm capsule connectedto a rod of which the displacements control the opening of the flapvalve; the rod comprises, advantageously, at its end distant from thediaphragm, a curved arm bearing an adjustable stop adapted to cooperatewith the abovesaid stepped cam.

A preferred embodiment of the invention will now be described in moredetailed manner with reference to the accompanying drawings.

FIG. 1 of these drawings shows diagrammatically, in elevation, withportions removed, a carburettor constructed according to the invention,and of which the elements occupy positions corresponding to the stoppedengine and at ambient temperature.

FIG. 2 is a section along the line II-II of FIG. 1, of certain elementsof the carburettor.

FIG. 3, lastly, shows similarly to FIG. 1, the carburettor with itselements in the positions which they occupy when the engine rotates atfast idling speed at an average temperature less than the normaltemperature of operation of the engine.

As regards the carburettor as a whole, it is constituted essentially bya principal pipe 1 provided with an air intake 2 and with a conventionalsystem for the introduction of the primary mixture (not shown).

As regards the starting device, it is constituted by an eccentric flapvalve 3 mounted on an axle 4 upstream of the abovesaid system (thedirection of flow is that indicated by the arrow of FIGS. 1 and 3) andactuated by the air flow sucked through the carburettor against theeffect of a first thermostatic member 5 (shown in FIG. 2) constituted bya bimetallic spiral which tends to close the flap valve when thetemperature of an element of the engine is less than a given limit.

The usual throttle member 6 of the carburettor is constituted by abutterfly valve mounted on an axle 7 downstream of the abovesaid systemand actuated by the usual accelerated control (not shown) which, when itis released, tends to bring back the said throttle member to its minimumopen position, this position being adjustable by a fast idling cam 8. Tothis end for example, this cam acts through steps 8a on an adjustablestop screw 10 borne by a lever 11, keyed on an axle l2 and connectedthrough a linkage 13 to a lever 14 fast to the axle 7 of the butterflyvalve 6.

The cam 8 is mounted freely on a fixed bush 15 (FIG. 2) on the inside ofwhich an axle 16 passes freely. The bush 15 is driven into a case 17which contains the thermostatic member 5; the case 17 is closed by a cap18 of insulating material, which supports the member 5 and an electricalresistance 19 connected to the ignition circuit of the engine so as tocause heating of the member 5 as soon as the engine rotates.

At the end of the axle l6, situated in the case 17, is fixed a lever 20,well visible in FIG. 2, extending radially from one side to the other ofthe axle l6 and curved at its ends in the direction of the axle 16. Theend 20a is curved towards the inside of the case 17 to constitute a sortof finger around which is wound the movable end of the thermostaticelement 5. This portion a will hence be drawn by the movable end of theelement 5. The other end 20b of the lever 20 is curved in the oppositedirection to the end 20a.

A lever 22 is fixed, by a nut 21, to the other end of the axle 16,spaced from the lever 20. The lever 22 is connected by a linkage 23visible in FIGS. 1 and 3, to a lever 24 fast to the axle 4 of the valve3.

The second thermostatic member 9 is constituted by a bi-metallic spiralwound around the bush 15, the central end of this spiral being made fastby anchoring to this bush and its opposite end 9a (FIGS. 1 and 3) beingradially curved and wound around a pin 25 fast to the cam 8. This end 9ais hence anchored to the cam 8 and the second member 9 can drive the cam8 either in clockwise direction or in the opposite direction.

This thermostatic member 9 is adjusted so that its end 9a moves inanticlockwise direction when it heats The whole is arranged so that,when the thermostatic member 5 heats up, it causes rotation of the cam 8in anticlockwise direction. To this end, a helical spring 26 (FIG. 2) iswound around the axle 16 between the bush l5 and the lever 22; one end26a of this spring is curved in the direction of the axle 16 and housedin a hole 27 of the lever 22. The other end 26b of the spring 26 isconstituted by a rectilinear part parallel to a radius of the cam 8,intended to cooperate with the pin 25 borne by this cam.

The lever 11, whose shape is clear from FIGS. 1 and 3, has one end 11acurved in a direction perpendicular to the plane of the whole of thelever 11. This end 11a is adapted to cooperate with a part 22a of thelever 22. The part 220 has the shape of an elbow oriented perpendicularto the average direction of the whole of the lever 22. Under theseconditions, when the opening of the butterfly valve 6 is actuated, thelever 11 will turn in clockwise direction about the axle 12 and its end1 1a will cooperate with the part 22a so that minimum opening is imposedon the valve 3.

The pneumatic means sensitive to the pressure which exists in the intakepipe 1 downstream of the butterfly valve 6, provided to actuate, bytheir movement, the opening of the valve 3 when the abovesaid pressurediminishes, are advantageously constituted by a capsule C (FIGS. 1 and3) with a diaphragm 28. This diaphragm 28 separates the capsule into twochambers 29 and 30.

The chamber 29 is placed at atmospheric pressure, whilst the chamber 30is connected through a passage (shown diagrammatically) to an orifice 31opening into the pipe 1 downstream of the butterfly valve 6. Thediaphragm 28 is gripped between two cups 32 and 33 and is coupled,through the latter, to a stem 34 extending parallel to a diameter of thecasing 17 and passing through the latter into a groove g (FIG. 2)provided for this purpose.

Substantially at its middle portion, the stem 34 comprises a notch ebounded, on the side distant from the diaphragm 28, by an edge 34a,perpendicular to the longitudinal direction of the stem 34. The end 201)of the lever 20 becomes lodged in the notch 2 so that the edge 340 cancooperate with this end 20b.

' A spring arranged in the chamber 30 and supported on the one hand,against the bottom of this chamber and, on the other hand, on the cup33, op-

poses the effect of the pressure on the diaphragm 28.

When the pressure at the level of the orifice 31 is sufficiently low,the diaphragm 28 moves towards the right from the position that itoccupies in FIG. I, to the position of FIG. 3, and the edge 34a of thestem 34 draws the end 20b so that the lever 22 turns in anticlockwisedirection, which forces the valve 3 to partly open.

This being the case, according to the invention, there are provided stopmeans B (FIGS. 1 and 3) with several positions, adapted to limit, invariable manner as a function of the position that they occupy, themovement of the pneumatic means and more specifically, of the stem 34.There are also provided means T sensitive to ambient temperature,adapted to control the position occupied by the stop means B.

These stop means B are constituted preferably by a stepped rotary camwhich is advantageously constituted by a peripheral portionp of the cam8, different from the zone including the steps 8a serving for theadjustment of the opening of the butterfly valve 6. This zone p includesalso steps 8b staggered angularly and such that, according to theposition occupied by the cam 8, the limit imposed on the movement of thestem 34 varies.

The stop means B being constituted by a portion of the cam 8, the meansT sensitive to ambient temperature are then constituted by the secondthermostatic member 9 of which the end is anchored on the pin 25.

The end 34b of the stem 34 is situated in a plane perpendicular to thelongitudinal direction of the stem 34 as seen in FIG. 2. The stem end3417 bears a screw 36 serving as an adjustable stop adapted to cooperatewith the steps 8b of the cam 8.

As a result of which, there is obtained a carburettor whose operation isas follows.

At low temperature, below 20 C, and before starting of the engine, theelements of the carburettor occupy the positions shown in FIG. 1. Thecam 8 actuated by the thermostatic element 9 is in a position such thatthe screw 10 is in abutment on a step 8a which ensures wide opening ofthe butterfly valve 6. Simultaneously, the distance which separates thescrew 36 from the steps 8b is slight so that, after starting of theengine, when the pressure in the chamber 30 tends to move the stem 34towards the right in FIGS. 1 and 2, the stroke of this stem will beslight. In consequence, the end 20b drawn by the edge 34a will have aslight movement and the valve 3 will be little opened, thus ensuring aconsiderable enrichment of the air-fuel mixture admitted to the engine,necessary by reason of the low ambient temperature.

For an average ambient temperature of the order of 20 C for example, theelement 9 imposes a position on the cam 8 (see FIG. 3) which is suchthat on the one hand, the butterfly valve 6 is further closed at idlingthan in the case of FIG. 1 and that, on the other hand, the screw 36comes into abutment on a step 8b which is closer to the axle 16 than inthe case of FIG. 1. As a result, the movement of the stem 34 under theaction of low pressure existing at the orifice 31, is greater even thanthe rotation of the lever 22. It follows that the valve 3, afterstarting of the engine, is open more than in the case of FIG. I, whichgives a lesser enrichment than at low temperature but sufficient for theengine to turn normally.

It will hence be quite clear that the valve 3, after starting of theengine, takes a precise position which depends on the ambienttemperature at starting and which is independent of the friction of thecontrol elements of the valve.

As soon as the engine rotates, the electrical resistance 19 (FIG. 2), isheated and transmits heat to the element 5 which is deformed and thenmakes the axle 16 and the lever 22 rotate in anticlockwise direction.After sufficient rotation of this axle 16, the end 26b of the spring 26drawn by the lever 22, engages with the pin 25; from this moment, it isthe rotation of the axle 16 which controls the rotation of the cam 8until the latter takes the position which corresponds to normal idlingand to an opening of the butterfly valve 6 less than that which it hadon starting. Simultaneously, the lever 22 by actuating the linkage 23 ofthe lever 24 fully opens the valve 3.

Thus, there is obtained a device which enables enrichment of theair-fuel mixture, at accelerated idling, which can be slight at ambienttemperatures in the neighbourhood of C, without however compromisingsound operation at lower temperature since this enrichment is thengreater.

1 claim:

1. Carburettor comprising a starting device with an eccentric flap valvesituated in an air intake of the carburettor upstream of an intakesystem for the primary air/fuel mixture, said valve being actuated bythe air flow inspired by the carburettor against the effect of a firstthermostatic member which tends to close said flap valve when thetemperature of an element of the engine is below a given limit, saidcarburettor comprising in addition a cam called a fast idling camadapted to cooperate with a second thermostatic member, said cam beingintended to partly open the usual throttle member of the carburettorwhen the flap valve is at least partially closed, pneumatic meanssensitive to the pressure in the intake pipe downstream of the throttlemember being provided to control, by their movement, the opening of thevalve when said pressure diminishes, said carburettor also comprisingstop means with several positions, adapted to limit, in variable manneras a function of said position that they occupy, the movement of thepneumatic means, and said second themestatic member constituting meanssensitive to the ambient temperature arranged to control the positionoccupied by the stop means.

2. Carburettor according to claim 1, wherein said stop means areconstituted by a stepped rotary cam, the

various angular positions taken by the cam being controlled by theambient temperature sensitive means.

3. Carburettor according to claim 2, wherein the stepped cam isconstituted by a peripheral part of the fast idling cam, different fromthe zone serving for the adjustment of the opening of the usual throttlemember, the second thermostatic member having one end anchored at afixed point and the other end anchored to the fast idling" cam.

4. Carburettor according to claim 3, wherein the end of the secondthermostatic member, which is anchored to the cam, is wound about a pinfast to the cam.

5. Carburettor according to claim 1, wherein th pneumatic means areconstituted by a diaphragm capsule controlling the movements of a stem,and the stem comprises, at its end distant from the diaphragm, a curvedarm bearing a screw constituting an adjustable stop, adapted tocooperate with the stop means in several positions.

6. Carburettor according to claim 5, wherein the stem comprises, in itsmiddle part, a notch bounded by an edge, adapted to cooperate with theend of a lever controlling the opening of the. flap valve, this leverbeing connected, at its other end, to the first thermostatic member.

7. Carburettor according to claim 6, wherein the lever connected to thefirst thermostatic member is keyed on the end of an axle rotating freelyin a bush on which is mounted free in rotation the fast idling cam, theother end of the axle emerges from the bush and bears an arm connectedto a linkage controlling the opening of the valve, the secondthermostatic member being mounted about the end of the bush neighbouringsaid arm and the fixed end of said second thermostatic member beinganchored in the bush.

8. Carburettor according to claim 7, wherein a helical spring is mountedaround the axle between the arm and the neighbouring end of the bush,said spring being anchored, at one end in said arm and at its other end,comprising a rectilinear part arranged to cooperate, for a sufficientrotation of the arm, with a pin fast to the cam so that the latter isrotated by the arm.

9. Carburettor according to claim 2, wherein the pneumatic means areconstituted by a diaphragm cap sule controlling the movements of a stem,and the stem comprises, at its end distant from the diaphragm a curvedarm bearing a screw constituting an adjustable stop, adapted tocooperate with the stop means in several positions.

1. Carburettor comprising a starting device with an eccentric flap valvesituated in an air intake of the carburettor upstream of an intakesystem for the primary air/fuel mixture, said valve being actuated bythe air flow inspired by the carburettor against the effect of a firstthermostatic member which tends to close said flap valve when thetemperature of an element of the engine is below a given limit, saidcarburettor comprising in addition a cam called a ''''fast idling''''cam adapted to cooperate with a second thermostatic member, said cambeing intended to partly open the usual throttle member of thecarburettor when the flap valve is at least partially closed, pneumaticmeans sensitive to the pressure in the intake pipe downstream of thethrottle member being provided to control, by their movement, theopening of the valve when said pressure diminishes, said carburettoralso comprising stop means with several positions, adapted to limit, invariable manner as a function of said position that they occupy, themovement of the pneumatic means, and said second thermostatic memberconstituting means sensitive to the ambient temperature arranged tocontrol the position occupied by the stop means.
 2. Carburettoraccording to claim 1, wherein said stop means are constituted by astepped rotary cam, the various angular positions taken by the cam beingcontrolled by the ambient temperature sensitive means.
 3. Carburettoraccording to claim 2, wherein the stepped cam is constituted by aperipheral part of the ''''fast idling'''' cam, different from the zoneserving for the adjustment of the opening of the usual throttle member,the second thermostatic member having one end anchored at a fixed pointand the other end anchored to the ''''fast idling'''' cam. 4.Carburettor according to claim 3, wherein the end of the secondthermostatic member, which is anchored to the cam, is wound about a pinfast to the cam.
 5. Carburettor according to claim 1, wherein thpneumatic means are constituted by a diaphragm capsule controlling themovements of a stem, and the stem comprises, at its end distant from thediaphragm, a curved arm bearing a screw constituting an adjustable stop,adapted to cooperate with the stop means in several positions. 6.Carburettor according to claim 5, wherein the stem comprises, in itsmiddle part, a notch bounded by an edge, adapted to cooperate with theend of a lever controlling the opening of the flap valve, this leverbeing connected, at its other end, to the first thermostatic member. 7.Carburettor according to claim 6, wherein the lever connected to thefirst thermostatic member is keyed on the end of an axle rotating freelyin a bush on which is mounted free in rotation the ''''fast idling''''cam, the other end of the axle emerges from the bush and bears an armconnected to a linkage controlling the opening of the valve, the secondthermostatic member being mounted about the end of the bush neighbouringsaid arm and the fixed end of said second thermostatic member beinganchored in the bush.
 8. Carburettor according to claim 7, wherein ahelical spring is mounted around the axle between the arm and theneighbouring end of the bush, said spring being anchored, at one end insaid arm and at its other end, comprising a rectilinear part arranged tocooperate, for a sufficient rotation of the arm, with a pin fast to thecam so that the latter is rotated by the arm.
 9. Carburettor accordingto claim 2, wherein the pneumatic means are constituted by a diaphragmcapSule controlling the movements of a stem, and the stem comprises, atits end distant from the diaphragm a curved arm bearing a screwconstituting an adjustable stop, adapted to cooperate with the stopmeans in several positions.